Coastal & Marine Geology InfoBank

Home FACS Activities Atlas Geology School Related Sites More

USGS CMG InfoBank: Accretion

Skip navigational links
Dictionaries: Our Mapping Systems   The USGS and Science Education   USGS Fact Sheets   Topics   Keywords   Data Dictionary   Metadata Dictionary   Computer Terminology   Digital Formats  
InfoBank Terms: Activity ID   activity overview   crew   digital data   formal metadata   lines   metadata   NGDC   port stops   project/theme   region   ship   stations   time   virtual globe   year  
Data Types: bathymetry   biological   geochemical   gravity   ground penetrating radar   imaging   LIDAR   logs   magnetics   metering equipment   navigation   samples   seismic   total station   definitions disclaimer  
Data Formats: ARC coverage   E00   FGDC metadata   gridded/image   imaging   material   scattered/swath   Shapefile   vector/polygon  
Comment: 05:53 - 07:05 (01:12)
Source: Annenberg/CPB Resources - Earth Revealed - 2. The Restless Planet
Keywords: "David Stevenson", "planetary formation", planet

Our transcription: The cloud of material from which the planets formed started out as being mostly gas with a small amount of dust.
That dust was very fine indeed, but the particles collided with each other, and during those collisions they stuck with each other, so that materials started to coagulate into still bigger bodies, so you have to imagine that we went from dust particles all the way up to objects that were kilometers across.
Those objects were colliding with each other making still bigger bodies, so that we think of the formation of solid planets like the Earth as being a hierarchical process, a process that starts off with very small things, very large in number, towards intermediate sizes things, smaller in number, and eventually ending up with a very small number of large objects.
As an intermediate stage in this process, we could imagine that the region where the Earth formed contained hundreds of objects that were about the size of the Earth's moon.
Most of those objects, then, coalesced to make a single planet, the Earth.

Geology School Keywords
Skip footer navigational links

Coastal and Marine Science Centers:  Pacific   St. Petersburg   Woods Hole  
InfoBank   Coastal and Marine Geology Program   Geologic Information   Ask-A-Geologist   USGS Disclaimer  

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information: InfoBank staff
Page Last Modified: Thu Oct 31 04:25:10 PDT 2013  (chd)